package org.study.mr;

import java.io.IOException;
import java.util.StringTokenizer;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.IntWritable;
import org.apache.hadoop.io.Text;
import org.apache.hadoop.mapreduce.Job;
import org.apache.hadoop.mapreduce.Mapper;
import org.apache.hadoop.mapreduce.Reducer;
import org.apache.hadoop.mapreduce.lib.input.FileInputFormat;
import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;

/**
 * @see {@linkplain https://www.cnblogs.com/zmt0429/p/6703504.html
 *      MapReduce编程初步（WordCount，TopN）}
 * @Title: WordCount
 * @Description:
 * @Author: zhaotf
 * @Since:2018年11月19日 上午9:06:53
 */
public class WordCount {

	/**
	 * 
	 * @Title: TokenizerMapper
	 * @Description:map端
	 * @Author: zhaotf
	 * @Since:2018年11月19日 上午11:13:55
	 */
	public static class TokenizerMapper extends Mapper<Object, Text, Text, IntWritable> {
		private final static IntWritable one = new IntWritable(1);
		private Text word = new Text();

		@Override
		public void map(Object key, Text value, Context context) throws IOException, InterruptedException {
			StringTokenizer itr = new StringTokenizer(value.toString());
			while (itr.hasMoreTokens()) {
				word.set(itr.nextToken());
				context.write(word, one);
			}
		}
	}

	/**
	 * 
	 * @Title: IntSumReducer
	 * @Description:reduce端
	 * @Author: zhaotf
	 * @Since:2018年11月19日 上午11:14:08
	 */
	public static class IntSumReducer extends Reducer<Text, IntWritable, Text, IntWritable> {
		private IntWritable result = new IntWritable();

		@Override
		public void reduce(Text key, Iterable<IntWritable> values, Context context)
				throws IOException, InterruptedException {
			int sum = 0;
			for (IntWritable val : values) {
				sum += val.get();
			}
			result.set(sum);
			context.write(key, result);
		}
	}

	public static void main(String[] args) throws Exception {
		Configuration conf = new Configuration();
		// String[] otherArgs = new GenericOptionsParser(conf,
		// args).getRemainingArgs();
		// if (otherArgs.length < 2) {
		// System.err.println("用法：wordcount <int> [<in>...] <out>");
		// System.exit(2);
		// }
		Job job = Job.getInstance(conf, "word count");
		job.setJarByClass(WordCount.class);
		job.setMapperClass(TokenizerMapper.class);
		job.setCombinerClass(IntSumReducer.class);
		job.setReducerClass(IntSumReducer.class);
		job.setOutputKeyClass(Text.class);
		job.setOutputValueClass(IntWritable.class);
		// for (int i = 0; i < otherArgs.length - 1; ++i) {
		// FileInputFormat.addInputPath(job, new Path(otherArgs[i]));
		// }
		// FileOutputFormat.setOutputPath(job, new
		// Path(otherArgs[otherArgs.length - 1]));
		FileInputFormat.setInputPaths(job, "/data/mapReduce/wordCount-1");
		FileOutputFormat.setOutputPath(job, new Path("/data/mapReduce/wordCount-1-" + System.currentTimeMillis()));

		System.exit(job.waitForCompletion(true) ? 0 : 1);
	}

}
